FSEvents on macOS doesn't detect SQLite WAL file changes

Problem

When using file watching (watchdog) to detect database changes on macOS, FSEvents doesn't reliably detect modifications to SQLite WAL files. This affects cross-process monitoring where a separate process watches for database changes.

Root Cause

FSEvents on macOS doesn't report changes to SQLite WAL files because:

1. WAL files are modified in-place without triggering typical file system events
2. FSEvents does "temporal coalescing" which may miss rapid changes
3. Changes go to the WAL file, not the main .db file

Upstream Issue

Blocked on: https://github.com/emcrisostomo/fswatch/issues/150

Workaround

Touch a marker file after database modifications (with debouncing) on macOS to trigger file system events that FSEvents will detect.

References

• https://github.com/emcrisostomo/fswatch/issues/150
• https://github.com/gorakhargosh/watchdog/pull/729
• https://sqlite.org/wal.html